1. Technical Field
The present disclosure relates to sector-shaped segment cores configuring a stator core for a rotary electric machine, and a method for manufacturing the segment cores, and more specifically, to sector-shaped segment cores configuring a stator core for a rotary electric machine which is applied to a motor, a generator or the like installed such as in an electric vehicle and a hybrid vehicle, and to a method for manufacturing the segment cores.
2. Related Art
Segment cores configuring a stator core for a rotary electric machine are known. FIG. 9 shows such segment cores 1 configuring a stator core. The segment cores 1 are arranged on the side of the outer periphery of a rotor that rotates about the rotary axis of a rotary electric machine. As shown in FIG. 10, the segment cores 1 form an annular stator core 2 which is spaced apart from the rotor by a predetermined distance. Each of the segment cores 1 is made up of laminated steel plates, each having a shape of a sector corresponding to the shape of a segment which is one of the circumferential divisions of the stator core 2. Each of the segment cores 1 has a yoke portion 1y that forms the annular outer peripheral portion of the stator core 2, and a two-toothed tooth portion it in which two teeth are extended toward the inner peripheral side of the stator core 2 from the yoke portion 1y. 
On the inner peripheral side of the stator core 2, a plurality of radially elongated open slots 3 are annularly arranged in the circumferential direction at regular intervals, for the insertion of windings, not shown. As shown in FIG. 11, when the segment cores 1 are manufactured, a plurality of rows of segment-core-shaped outlines (hereinafter also referred to as “segment outlines”) 1a are arrayed with minimum gaps therebetween on a thin electromagnetic steel plate as a sheet member 5 unwound from a wound-up state. The segment outlines 1a on the sheet member 5 are sequentially punched using a puncher, not shown, for a plurality of times on a section-by-section basis to finally cut out segment core members 1b. The cut-out segment core members 1b are laminated to obtain a segment core 1. These type of segment cores has been well known as disclosed in JP-A-2002-320351.
In the conventional method of manufacturing the segment cores is as set forth above, each segment outline 1a has a shape of a sector. Therefore, when a plurality of rows of such segment outlines 1a are arrayed on the sheet member 5, excess regions 5a, which are not enclosed by the segment outlines 1a, are left on both longitudinal edge portions of the sheet member 5. Further, each of the segment outlines 1a has a slot-predetermined portion 3a on the outside thereof. Therefore, these slot-predetermined portions 3a also turn out to be the excess regions 5a left not enclosed by the segment outlines 1a. Such excess regions 5a and 3a will end up with wastes after the segment core members 1b are punched out. The total area occupied by the excess regions 5a and 3a in the sheet member 5 is comparatively large. Such large excess regions have raised a problem of deteriorating material yield in manufacturing segment cores.